Air and fuel inlet for furnaces



Oct. 3l, 1939. G. A. KoHouT AIR AND FUEL INLET Fon FURNAcEs Fiyled March 6, 193e ,U n i u ...m f w .w fwd mK y mm @a Um f e NM w a f/ ffl,

Patented Oct. 31, 1939 Nien srir :f

ermee 2 Claims.

This invention. relates to coal feeding devices for furnaces and particularly to a combined feed screw and air blast unit for directing coal into the fire box of a furnace and spreading the same T over the grates in the furnace.

In a copending application Serial No. 67,471, filed March 6, 1936, for Coal feeding device for furnaces.' I have shown a general mechanism for feeding fuel in which this unit is utilized.

Av It is the principal purpose of this invention to provide in combination a feed screw for advancing fuel into a furnace, an inclined chute for imparting to the fuel after it leaves the screw a certain speed downwardly and toward the re box of the furnace, and an airblast for taking the fuel as. it leaves the incline and giving the same a further horizontal impetus whereby to Fig. 1 is a vertical sectional view through a` fuel feeding unit embodying the invention; g5V4 Fig. 2 is a sectional view taken substantially on the line 2-2 of Fig, 1;

Fig. 3 is a sectional view on the line 3-3 of Fig. 1; and

Fig. 4 is an enlarged sectional View taken on 3i),n the line -t of Fig. 2.

' Referring now in detail to the drawing, the present invention is adapted to be applied to any furnace having a. re box and a grate or other suitable fuel support therein. The fuel feeding device comprisesV a supporting channel iron 5 adapted to be secured in any suitable fashion to a front plate E of a furnace. An angle iron 'I may be also used to aid in support of the fuel feeding device, and the front refractory wall 8, which is usually provided in a furnace of this character, is apertured to receive the fuel feeding device.

The fuel feeding device itself comprises a tubular housing comprising an iron casting 9 which has a forwardly projecting lip I0 resting upon the channel iron 5. The housing 9 is substantially rectangular in exterior conformation and has supporting flanges II and I2 at the lower side edges thereof as will be readily understood from an inspection of Fig. 3. The housing 9 has a hollow portion I3 which is provided with a cylindrical lower surface I4. This cylindrical surface extends forwardly over the lip I0. At

its other end from the lip IU, the housing 9 has an end wall I5 which partially closes the end of illustrated clearly in Fig..1, at I'I so that the 5f` housing 9 is provided with a downwardly directed opening i3 at the fire box end thereof. A feed screw I9 is suitably supported by means of a plate 2l! carried by the channel iron 5.

rIhis feed screw, it will be noted, has a portion 1I) overlying the lip Iii to receive fuel from a suit able hopper or other source and extends substantially all of the way to the inner end of the bottom portion It of the housing 9. Any suitable means may be utilized for rotating the feed 15` screw Ill as will be readily understood. Rotation of the feed screw I9 will advance coal toward the opening IB, and the coal will drop from the housing 9 when it reaches the end I'I. of the bottom portion It. 20.

Adjacent the opening IS and below the hous'-v ing 9, there is provided a second casting 2I` which casting rests upon the refractory kwall 8 and supports the housing 9. This casting 2| is in the form of a blockhaving an aperture 22 there- 25,

in which aperture is divided into two. portions, a wide portion 23 being provided at the outer end of the block 2l, and a reducedportion 24 extending rearwardly from the wire portion 23 to the rear or fire box end of the block 2|. block 2l provides a slopingupper wall for'the aperture 22 which serves to restrictthe passage through the block 2| toward the fire box endA thereof. f

Beneath the reduced portion 24 of the open- 35 ing through the block 2|, I provide a groove which is adapted to receive a plate 26. The plate 26 is free to move within its groove so that this plate may be adjusted to extend a greater or less amount beyond the fire box end of the block 40 2i. The downwardly sloping surface 25 terminates short of the fire box end of the block ZI, and the opening into the fire box has an upper wall 2l which cooperates with the plate 26 to produce a flat channel through which a blast of 45 air may be directed into the fire box.

It will be noted that the plate 26 projects out a substantial distance beyond this flat channel so as to provide a shelf portion 28. The block 2l is extended up to meet the terminal 50 end Il of the bottom wall I4 of the casting 9. The block is sloped downwardly asindicated at SI to provide an inclined chute. The surface 3|, which forms the bottom wall of this chute, makes an angle of about 45 to the horizontal. 55

The 30.

It will be evident that, if coal of the mixed size be fed into the casting 9 by means of the screw I9, this coal will be pushed onto the inclined surface 3| and will roll down the chute so as to drop across the air channel and strike the shelf 28. Movement down the inclined surface 3| imparts to the coal a substantial momentum particularly to the larger particles thereof, and this momentum has both a Vertical component and a horizontal component. When the fuel particles strike the shelf 28, their tendency is to rebound, and the larger particles actually do strike the shelf 28 and rebound therefrom so that they leave the shelf 28 in a direction which is nearly horizontal but slightly upward and toward the fire box. It is obvious that the real fine particles and dust in the coal do not rebound as readily from the shelf 28 so that they would ordinarily have a tendency to pile up on the shelf and block it so as to prevent rebounding of the larger particles. The air channel provided by the aperture 22 is utilized to keep the fine particles and dust off the shelf 28 and to spread them out into the furnace fire box as Well as to give a greater forward impetus to the larger particles of coal.

To produce an air blast through the aperture 22, I provide an air nozzle 32 which has a flattened outlet 33 lying on the plate 26. At the sides, the nozzle 32 flares outwardly toward the outlet 33, and the nozzle is provided with a restricted neck at 34 adjacent its inlet 35. Any

suitable mechanism can be used to direct a blast of air through the nozzle 32. It will be noted that the discharge from the outlet 33 of the nozzle occurs directly in front of the throat of the restricted part 24 of the aperture 22. This causes the air blast through the nozzle 32 to entrain air and t0 draw it in through the aperture 22 to thereby create a blast through the flat air channel underneath the wall 21 which is suiciently strong to force any fuel particles that may tend to lodge on the shelf 28 out into the fire box.

The ne coal, as it drops off the inclined chute 3|, never reaches the shelf 28, but is blown directly into the fire box by the force of the blast. The heavy or larger particles of coal, however, rst pass through the blast where they get more horizontal motion and then rebound from the shelf 28 so as to remain for a substantial horizontal movement directly in the zone of' the air blast. This causes the particles to be scattered well out into the re box over the grate and prevents their piling up adjacent the refractory wall 8.

I have shown a suitable means for inducing an air blast in the nozzle 32 which means consists of a steam jet nozzle 36 constructed as shown in Fig. 4. This steam nozzle 36 is fed from a pipe 31, a gauge 38 being provided to measure the steam aperture. The steam is controlled by a valve 39 and is taken from a steam header 48 that extends across in front of the furnace beneath the channel iron. 5.

From the above description, it is believed that the construction and operation of this device will be readily apparent to those skilled in this art. It is also believed to be evident that various modifications may be made without departing from the scope of the invention as illustrated by the accompanying claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A fuel feeding unit of the character described comprising in combination, a tubular feed screw housing, a feed screw therein, said housing having one end open in an axial direction and said feed screw having a portion projecting from said open end, an outlet at the other end of said housing, a hollow block beneath said housing and having a sloping face extending downwardly and away from the feed screw beneath said outlet, said block having a projecting shelf mounted thereon and spaced below said sloping face, said block having an opening therethrough between said sloping face and said shelf, said projecting shelf comprising a plate, and said block having grooves therein receiving the opposite side edges of said plate.

2. In a fuel feeding unit wherein fuel is advanced by a feed screw from a hopper through a housing for the screw and discharged downwardly from the housing, a hollow block mounted beneath said housing and having a sloping face extending downwardly and away from the housing beneath the discharge outlet thereof, said block having a projecting shelf mounted thereon and spaced below said sloping face, said block having an opening therethrough between said sloping face and said shelf, said opening having a wide flat outlet directly over said shelf, and a uid blast nozzle in said opening behind the outlet thereof, said nozzle having a restricted throat and a steam jet nozzle mounted on said first named nozzle and directed into said throat.

GEORGE A. KOHOUT.

atl 

